The terms oils, fats, butters and waxes have been misused over the years. The historical definition of wax has previous been given. Butters, oils and fats are all triglycerides. Typically a titer point is used to characterize triglycerides. Titer point is very similar to melt point, but is much broader. Due to this wide melting range, it is possible to hold a triglyceride at a specific temperature and have some of the more solid components separate out. Thus the term “titer point” simply refers to the cloudiness that occurs as the lower melting portions start becoming liquid. In direct contrast to a natural triglyceride, a glycerin triester will have a very sharp melt point, typically around 3 degrees from when it starts sweating to when it completely liquefies. Typically they are divided into categories based on their physical nature. Since typically naturally derived triglycerides are specific mixtures of fatty groups, they are characterized by their titer point. Fats have a titer point of over 40.5° C., oils have a titer point of below 40.5° C. Butters have a titer below 40.5° C. but above 20° C. Oils are liquid at room temperature and we now use this word to describe any compound that is a liquid and is insoluble in water.
Butters are very specific triglycerides that are very desirable in the personal care market because they are soft semisolids, liquefy under pressure and provide a cosmetically pleasing feel on the skin. In nature there are basically two butters, coco butter and shea butter. The two butters have the same distribution of alkyl groups, but the position on which the groups are placed by enzymes accounts for the difference between the two.
Triglycerides are the tri-esters of glycerin with three equivalents of organic acid. Fatty acids are defined as those acids having alkyl or alkylene groups being C-5 and higher. The classical organic reaction follows it generally occurs at a temperature of between 150 and 200° C.

Having to reach a temperature of 150-180° C. is impossible for living organisms as water would boil and the organisms would die. Living systems perform this chemistry at 37° C. using enzymes. Enzymes are macromolecular biological catalysts. They are responsible for thousands of metabolic processes that sustain life. There is an extraordinary amount of specificity to the way the enzyme systems work. In fact enzymes are so specific, that in 1894 Emil Fischer stated that both the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another. This is often referred to as “the lock and key” model.
All living systems have the ability to synthesize triacylglycerols, and the process has been studied intensively in plants and animals especially. Many cell types and organs have the ability to synthesize triacylglycerols, but in animals the liver, intestines and adipose tissue are most active with most of the body stores in the last (see our web page on triacylglycerol composition). Within all cell types, even those of the brain, triacylglycerols are stored as cytoplasmic ‘lipid droplets’ (also termed ‘fat globules’, ‘oil bodies’, ‘lipid particles’, ‘adiposomes’, etc) enclosed by a monolayer of phospholipids and hydrophobic proteins, such as the perilipins in adipose tissue or oleosins in seeds. These lipid droplets are now treated as distinctive organelles, with their own characteristic metabolic pathways and associated enzymes—no longer boring blobs of fat. They are not unique to animals and plants as Mycobacteria and yeasts have similar lipid inclusions.
The lipid serves as a store of energy, which can be released rapidly on demand, and as a reserve of essential fatty acids and precursors for eicosanoids. However, lipid droplets may also serve as a protective agency to remove any excess of biologically active and potentially harmful lipids such as free fatty acids, diacylglycerols, cholesterol (as cholesterol esters), retinol esters and coenzyme A esters.
Two main biosynthetic pathways are known, the sn-glycerol-3-phosphate pathway, which predominates in liver and adipose tissue, and a monoacylglycerol pathway in the intestines. In maturing plant seeds and some animal tissues, a third pathway has been recognized in which a diacylglycerol transferase is involved. Triacylglycerol biosynthesis in plants is discussed in greater detail in a separate webpage on this site. The most important route to triacylglycerol biosynthesis is the sn-glycerol-3-phosphate or Kennedy pathway illustrated below, first described by Professor Eugene Kennedy and colleagues in the 1950s, by means of which more than 90% of liver triacylglycerols are produced.
The result of enzymatic biosynthesis is that each hydroxyl group on the glycerin is very specifically substituted by a controlled reaction in which a very specific fatty group is added.
As stated there are two natural butters. Synthetic butters or trans-fats are made by a synthetic or not natural method. Most synthetic butters sold into the personal care market are the result of partial hydrogenation. Any natural oil that contains unsaturation, can be made into a butter by partial hydrogenation. Soybean oil, olive oil or other unsaturated oils when hydrogenated are hardened to provide a mixed saturated/unsaturated product. Therefore in must be clear that most synthetic butters sold in the personal care market are the fruit of partial hydrogenation. Partial hydrogenation is very undesirable due to the fact that: The product contains some unsaturation, either a single unsaturation or two unsaturated groups. The presence of the unsaturation makes the triglyceride susceptible to oxidation in a process called rancidity. Rancidity breaks the double bond into aldehydes having half the molecular weight as the starting material. The resulting aldehyde has an unpleasant aroma and is unacceptable in cosmetic products. Triglycerides that undergo this process are said to be rancid. Rancidification is the process that causes a substance to become rancid, that is, having a rank, unpleasant smell or taste. Specifically, it is the autoxidation of fats into short-chain aldehydes and ketones, which are objectionable in taste and odor.
A major health concern during the partial hydrogenation process is the production of trans fats. Trans fats are the result of a side reaction with the catalyst of the hydrogenation process. This is the result of an unsaturated triglyceride (also called fat), which is normally found as a cis isomer converts to a trans isomer of the unsaturated fat. Isomers are molecules that have the same molecular formula but are bonded together differently. Focusing on the Sp2 double bonded carbons, a cis-isomer has the hydrogen atoms on the same side. Due to the added energy from the hydrogenation process, the activation energy is reached to convert the cis isomers of the unsaturated fat to the thermogenically favored trans isomer of the unsaturated fat. The effect is putting one of the hydrogen atom on the opposite side of one of the carbons. This results in a trans configuration of the double bonded carbons. The human body doesn't recognized trans fats.
While the digestive system treats hydrogenated fats as food, the bloodstream cannot use it. The cells simply try to store the trans fats and deposits them on the artery walls. Ironically, fat that has been completely hydrogenated does not actually contain trans fat; only the partially hydrogenated oil has been shown to cause arterial buildup. However, full hydrogenation makes the oil so hard that it is not usable on its own.
Because they are not metabolized, Trans fats have been linked to an increased risk of coronary heart disease, in which plaque builds up inside the arteries and may cause a heart attack.
The FDA can act when it believes a food ingredient is, in fact, not GRAS (Generally regarded as safe). And that's what the agency's preliminary determination is doing now with partially hydrogenated oils. A Federal Register notice was published on Nov. 7, 2013 announcing the preliminary determination that partially hydrogenated oils are not GRAS, which includes the opening of a 60-day public comment period.
If FDA makes a final determination that PHOs as foods are not GRAS, the agency and food industry would have to figure out a way to phase out the use of PHOs over time. To help address this concern in an appropriate manner, the Federal Register notice calls for comment on how long it would take the food industry to phase out its use of PHOs.
There is ample literature to suggest that trans fats that are applied to the skin will undergo an enzymatic reaction releasing trans fatty acids which as far back as 1989 have been identified as skin penetration enhancers. (Pharm Res 1989 Mar. 6(3): 244-7). This study found that there was “no significant difference between cis and trans unsaturated C16-C18 fatty acid isomers in their effects on naloxone flux, and that all unsaturated fatty acids are more effective enhancers than the corresponding saturated isomers”.
Food Chemistry 81 (2003)453-456 discloses that partial hydrogenation of soybean oil results in around 7% trans isomer.
While the FDA currently limits it's activities to food, it makes little sense to apply of butters containing trans fats to the skin.
An article entitled transcutaneous absorption of topically massaged oil in neonates published in the Indian pediatrics 2000 542:998-1005 looked at the application of oils on newborns and concluded that topically applied oils can be absorbed into neonates is probably available for nutritional purposes.
In order for a butter to be of interest to the personal care market, it must be (1) soft at room temperature; (2) must not “crack” when handled; (3) must be able to be applied to the skin at ambient temperature by rubbing; (4) must liquefy upon rubbing, (5) must be free of rancidity and (6) must be free of trans acids that are the result of partial hydrogenation. For unsaturated oils to be made into butters, partial hydrogenation is the most common approach.
Prior to the current invention there has not been disclosed a butter for personal care applications that (1) is soft at room temperature; (2) does not “crack” when handled; (3) can be applied to the skin at ambient temperature by rubbing; (4) will liquefy upon rubbing, (5) will provide an aesthetically appealing feel when applied; (6) is free of rancidity and (7) is free of trans acids that are the result of partial hydrogenation.